def f(n):
    d = 2
    while d * d <= n:
        if n % d == 0:
            return False
        d += 1
    return True
d = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"]
a = input().split()
if len(a) != 3 or a[0] not in d or a[1] not in d or a[2] not in d:
    print("Wrong input")
else:
    n = int(str(d.index(a[0])) + str(d.index(a[1])) + str(d.index(a[2])))
    for i in range(1, 1000):
        if f(n - i):
            print(n - i)
            break
        if f(n + i):
            print(n + i)
            break
        
    

